Closes#853
## What
Adds a `reread` waste signal: identical `tool_result` content appearing
at more than one message position means the agent re-fetched something
already in context — the dominant failure signature of over-compression
(Manus context-engineering; JetBrains "Complexity Trap",
arXiv:2508.21433). Per-request savings can't see this cost; this signal
makes it visible.
- `WasteSignals.reread_tokens` — new field, in `total()`, exported as
`"reread"` in `to_dict()`.
- `parse_messages()` groups `tool_result` blocks by their **existing**
`content_hash` and counts every repeat beyond the first serve. No new
hashing or tokenization; one O(blocks) dict pass.
- `REREAD_MIN_TOKENS = 50` guard: short outputs ("ok", empty diffs)
legitimately repeat and are skipped. Duplicates within a single message
(same `source_index`) are not counted.
- Works across all formats the parser already normalizes to
`tool_result` blocks: OpenAI `role=tool`, Anthropic `tool_result`,
Strands/Bedrock `toolResult` (#813/#815).
- Flows through existing generic plumbing with zero handler changes:
pipeline → `RequestOutcome.waste_signals` → Prometheus
`headroom_waste_signal_tokens_total{signal="reread"}` → dashboard "Waste
Detected" panel. Dashboard gains label/color entries for the new key.
## Tests
7 new tests in `tests/test_parser.py::TestRereadDetection` (red before,
green after): OpenAI + Anthropic format detection, repeat-counting
semantics (first serve free), single-occurrence, short-duplicate guard,
same-message guard, `total()`/`to_dict()` participation. Updated 2
exact-shape assertions in `tests/test_config.py`.
Local runs: `tests/test_parser.py` (72 passed), `tests/test_config.py` +
outcome/reporting/observability/storage/proxy-hooks suites (190 passed),
`tests/test_canonical_pipeline.py` +
`tests/test_proxy_pipeline_lifecycle.py` (11 passed). `ruff check` +
`ruff format --check` clean.
## Real behavior proof
**Setup:** macOS (Darwin 25.5), Python 3.11.9, this branch, real proxy
server (`python -m headroom.proxy.server --port 18970
--anthropic-api-url http://127.0.0.1:18971`) with a local mock Anthropic
upstream returning a canned `/v1/messages` response (no real key
needed).
**Steps:** POSTed an Anthropic-format conversation to the live proxy:
agent fetches a 14 KB JSON log array via `get_logs` tool, then fetches
the identical content again under a different `tool_use_id` (the
re-read).
**Observed result** — `curl http://127.0.0.1:18970/metrics` after the
request:
```
# HELP headroom_waste_signal_tokens_total Tokens attributed to detected waste signals
# TYPE headroom_waste_signal_tokens_total counter
headroom_waste_signal_tokens_total{signal="json_bloat"} 9858
headroom_waste_signal_tokens_total{signal="reread"} 4935
```
`reread` = 4935 tokens, exactly the second serve of the ~4.9k-token tool
result (json_bloat counts both occurrences ≈ 2×). `/stats` shows the
same: `"waste_signals": {"json_bloat": 9858, "reread": 4935, ...}` —
which is what the dashboard panel renders.
Also verified the negative path live: a conversation whose tool results
contain non-compressible plain code text produced no waste-signal
entries (the pipeline only attributes waste when compression actually
engaged, unchanged behavior).
**Not tested:** Gemini `functionResponse` path (parser doesn't produce
`tool_result` blocks for it — pre-existing gap tracked in #819);
dashboard rendering only verified via the `/stats` payload the panel
binds to, not a browser screenshot.
## Out of scope (per #853)
Tool-call argument matching, compression-marker attribution,
tokens-per-task metric, cache hit-rate panel.
---------
Co-authored-by: Ash Rhodes <ashley.rhodes@king.com>
`.gitattributes` declares `*.py text eol=lf` and `*.sh text eol=lf`, but
74 files (73 .py, 1 .sh) are stored in the index with CRLF line endings,
violating that contract. Every macOS/Linux clone reports these files as
"modified" on fresh checkout because git's diff engine sees the stored
bytes don't match the attribute contract, even though the working tree
and index match byte-for-byte.
Running `git add --renormalize .` rewrites each affected blob so the
stored form matches the attribute declaration. No semantic changes —
every affected file's diff is "N insertions, N deletions" with inserts
and deletes being the same lines modulo line endings.
Follow-up commit adds `.git-blame-ignore-revs` so `git blame` / GitHub
blame skip this mechanical commit.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
